Current and presumably also future deployment scenarios require, as a matter of principle, a high level of flexibility in the use of missiles, projectiles and bombs, insofar as they are to be deployed against targets on or near the ground and can particularly be located in an urban environment.
For this purpose, effector system concepts, among other things, have been proposed in which flexible power control is enabled with the aid of two initiation devices for controlled deflagration and classic detonation of the blasting charge. It is thus possible to implement different modes of action, ranging from mere deflagration, as the smallest effect, to time-staggered combined reaction mechanisms, as intermediate effect, to detonation as the greatest effect.
In subdetonative output modes, particularly in the smallest mode of the deflagration of the blasting charge, relatively large fragments occur during disintegration of the shell, which can be attributed to low quasistatic pressures. This results in two drawbacks. For one, the fragment density is so low in these cases that military targets cannot be hit and damaged or destroyed even if they are in short range. For another, large fragment masses, in combination with low fragment speeds, increase the damage ranges of the warhead, which can be undesirable, particularly in the case of noncombatant/military persons and objects. The so-called collateral damage ranges are thus enlarged.
The size and shape of the fragments, besides on the blasting charge and the ignition thereof, depends substantially on the L/D ratio of the warhead and the material characteristics of the warhead shell. These are the wall thickness and quasistatic characteristics such as tensile strength, tensile yield point and elongation at rupture. The stresses occurring as a result of the expansion of the shell in the circumferential direction lead to typical shear fractures. Particularly in metals with a low tensile strength and ductile behavior (high tensile yield point and elongation at rupture) and/or cylindrical shells, the shell fragments can be very long and even extend over the entire length of the warhead shell.
Passive measures for the controlled breakdown of fragments such as the weakening of the warhead shell and/or additional inert inserts between shell and blasting charge work only under certain conditions. What is more, such measures may not be applicable in cases in which a given shell must be used and/or changes to the aerodynamic characteristics and/or physical characteristics (such as center of gravity, mass and moments of inertia) of the shell are not possible for reasons of compatibility. This practically rules out the use of such described passive measures from the outset.
An object of the present invention is therefore a device which enables controlled fragment formation even under the pressures occurring in the smallest output mode. In this way, the fragment masses can be significantly reduced and, simultaneously, the fragment density increased. As a result, the effect against near-range military targets can be improved while simultaneously reducing collateral damage ranges.
It is known to use various devices in warheads in order to break the warhead or munitions shell down in a controlled manner into fragments of a desired size and mass even in the case of subdetonative outputs with significantly smaller pressures than in a detonation.
Passive measures such as notches in the outer shell have only limited success depending on the notch depth and the shell material, which often manifests itself as fragments that are larger than intended.
Passive measures in the form of various inserts between warhead shell and blasting charge, such as diamond pattern inserts, perforated inserts, and notched rings lead to similar difficulties during the controlled breakdown of the outer shell. However, some inserts work so well that they generate small, additional fragments which can improve the effect, particularly against soft, near-range targets.
On the whole, it turns out that a good separation of the fragments in the circumferential direction is possible in the manner in which they occur as a result of the expansion of the shell even in the case of small quasistatic pressures and expansion rates, such as in the smallest mode of action. What proves problematic is, above all, the breakdown in the axial direction, particularly in the case of disadvantageous material characteristics and shell shapes. This is particularly evident in the shell ends, where the breakdown is typically poorer than in the center of the shell, with greater reaction speeds and pressures.